For users with healthy eyes, when the objects viewed are smaller or farther, it is difficult for the eyes to observe desired details. For example, when persons sit in farther positions to view a ball game, it is difficult to view the details of limb movement and expressions of athletes. For users whose eyes per se have shortsightedness or farsightedness, when the objects viewed are smaller or farther, it is more difficult for the eyes to identify the details of the objects or persons viewed. Conversely, when the objects viewed are too large or too close, it is difficult for the users to observe the global information of the gazed at objects. For example, when the users stand in front of a high building or a mountain, it is difficult to observe the overall situation of the high building or the mountain.
Conventional optical scaling devices, such as a telescope or a magnifier usually adopt global unified scaling. FIG. 1a is a schematic diagram of the view of a user, wherein A, B, C represent three objects in the view 110. Assuming that the user wants to amplify the viewing object B, as shown in FIG. 1b, when a global unified scaling mode is adopted, the object B is amplified and meanwhile, the object C is also amplified, while the object A is out of the view 110, that is, at this moment, the user cannot see the object A. Thus, global unified scaling will cause a change in the integral view of the user. In many scenes, such as AR (Augmented Reality) environment, they will bring discomfort to the user, causing inconvenience for use.